By Charles C. Mann

1) My article "is entirely about quantity of [petroleum] supply," when "mainstream analysts see 'peak oil' emerging not in supply but in demand." The purported lack of demand is because "oil has become uncompetitive even at low prices."

2) One of "many errors" in my article is my claim that economic growth and energy use are tightly linked.

3) Germany is not emitting more carbon dioxide today, no matter what I say in my article.

4) Renewable energy sources like solar power and wind power are cheaper than oil and natural gas (this is similar to the first critique).

5) Renewables do not "require massive storage and intercontinental transmission."

Each claim is incorrect. I will treat them in order.

1) Peak Oil. Contrary to Lovins, "mainstream analysts" do not see "peak oil" as a question of demand, rather than supply. In The Quest (2011), Daniel Yergin, probably the world's best-known energy analyst, describes "peak oil" as "the fear that the world is near or at the point of maximum output, and that an inexorable decline has already begun, or is soon to set in." The first page of Peaking at Peak Oil (2012) by Kjell Aleklett, president of the Association for the Study of Peak Oil and Gas, the most important peak-oil group, defines it as the "point in history when oil production reaches a maximum possible rate, Peak Oil, before declining." "Since 2005," Aleklett goes on to say, "our use of oil has been limited by production, not demand." In other words, "mainstream analysts" see peak oil in precisely the opposite terms from those used by Lovins.

Is "oil uncompetitive even at low prices"? Lovins's assertion is glib, to put it kindly. His stated example is the "uncompromised, oil-free U.S. automobile," which he argues could run far more cheaply than a standard gasoline vehicle. Lovins' source for this claim is Reinventing Fire, whose principal author is ... Lovins. The automobile in Reinventing Fire is Lovins' "hypercar," an ultralight electric/hydrogen/biofuel vehicle which in various incarnations he has been futilely urging carmakers to produce since 1991.

Why has no business raced to build the hypercar, despite its supposedly obvious advantages? One reason is that much of the fuel savings depends on its construction from carbon-fiber composite materials (compared to heavy vehicles, lighter vehicles need less energy to reach a given speed). Unfortunately, as Lovins has admitted, the task of "inserting composites into a steel car raises numerous, often costly and sometimes intractable compatibility issues" that automakers can only overcome by switching "to extensive, whole-platform 'clean-sheet' applications" -- that is, by scrapping their entire existing manufacturing system, an expensive prospect.

In sum, Lovins is touting the future economic benefits of new technologies but neglecting the initial costs. These are considerable. In Reinventing Fire, Lovins estimates that achieving these savings will require American consumers and businesses to invest $2 trillion. One thesis of my article: Americans will be less likely to spend trillions on fancy no-oil cars if cheap petroleum is in abundant supply.

2) Economic growth and energy use. Lovins says that I back my argument that energy and economic growth march together "by citing only global data (mixing early-stage developing with industrialized economies) for all forms of energy (diluting oil and gas with cheap coal and hydropower) for 1900-2000." Apparently, Lovins did not read the next paragraph of my article, in which I describe the lockstep association between energy-price spikes and economic recessions in the postwar United States.

As Lovins observes, I did lump together developed and developing countries and multiple types of energy. Because I was making a global argument, this procedure seemed entirely appropriate. As one zooms in, the details of the relationship between energy supplies and economic growth change. But everywhere on the planet, as the Australian economic historian David Stern has recently argued, energy remains a primary constraint on growth -- the point I was making in my article.

3) German carbon dioxide emissions. Lovins is correct that during the last decade coal-fired electricity declined in Germany as the country shifted toward renewables. But since 2011, when the government decided to abandon nuclear power, Germany has significantly increased its reliance on coal, as I described in my article. Contrary to Lovins' implication, this rise is not a blip: In April, Germany announced plans to raise its coal-fired generation capacity still further. Why is this? Presumably, Germany, a nation admirably committed to green energy, would choose solar and wind power if, as Lovins suggests, those forms of energy were the cheapest alternative. Unfortunately from a climate-change perspective, they are not.

Lovins then adds: "Despite economic growth, German carbon emissions fell 2.8 percent in 2011; in 2012 they rose 1.6 percent due to a cold winter but fell after weather-adjustment." This is doubly inaccurate. First, the figures Lovins quotes refer to the change in total greenhouse-gas emissions, not carbon emissions. Second, the nation's total carbon-dioxide output actually rose two percent, according to the German environmental agency, because of increased use of coal and natural gas. Worse, the biggest part of the increase was from lignite, the dirtiest kind of coal. It would be more accurate to say that Germany's carbon-dioxide emissions have risen slowly but inexorably since 2009, even as U.S. emissions have declined, as rising coal consumption has offset increased deployment of renewables.

4) Costs of renewables. To counter my statement that the cost of renewable energy is not yet equivalent to that of fossil fuels, Lovins cites two examples -- or, rather, one-and-a-half examples, because even he admits that wind power is only sometimes competitively priced. But a couple of anecdotes don't answer the question I raised, which is the typical or average cost of renewables versus that of fossil fuels.

The question is difficult to answer, because the cost structure of renewables and fossil fuels are different. But the U.S. Energy Information Agency does model the "levelized costs" for new power-generating facilities (levelized costs, it says, are "a convenient summary measure of the overall competiveness of different generating technologies"). According to the most recent EIA estimate, new natural-gas facilities in 2018 will cost an average of $67.10/megawatt-hour, whereas typical wind systems will cost $86.60/MWh, a substantial difference. Solar photovoltaic systems fare still worse. They will cost $144.30/MWh, more than twice as much as natural gas.

Again, this type of comparison is difficult to make. It is not easy to decide which factors to include or leave out. But it is hard to conclude, as Lovins does, that renewables are now cheaper than oil and gas without making a raft of unusual assumptions.

5) Energy storage. Lovins claims that "proven modern utility practice" means that renewables can be widely deployed without causing problems in the electricity grid. Germany, he says, is an example. Exactly the contrary is true. As three German energy researchers wrote in Energy Policy in November, ramping up renewables "carries the risk of grid instabilities causing damage to electronic devices and power outages ... As periodically volatile consumption meets weather-dependent production, the exact balancing of demand and supply already is and will become a complex challenge. This is one of the most critical issues in the transition to less carbon-emitting energy supply systems within the next decades" (citations omitted).

In renewable leader Germany, these problems are not theoretical. According to a March report from five researchers at the German Fraunhofer Institute for Wind Energy and Energy System Technology, the nation's high level of wind and solar power is already leading to reverse power flows in the distribution system as well as black- and brownouts. Indeed, German industry experienced 206,000 blackouts in 2011 (the figure comes from the Association of German Industrial Energy Companies).*

And the problems are spilling beyond Germany's borders. As the Institute of Energy Research noted in January, Germany's "transition to these intermittent green energy technologies" is not only "causing havoc" to its own electric grid, it is sending so many unplanned power surges into neighboring nations that these countries "are now building switches to turn off their connection with Germany at their borders." To add insult to injury, Germans are paying some of the highest residential energy prices in Europe. (Is it necessary to add that the high prices are not a sign that renewables are cheaper than fossil fuels?)

Lovins goes on to give some examples of where wind and solar power have provided a relatively large share of the power in the electric grid for short periods of time. This is a fine thing, but irrelevant to the larger question about whether intermittent renewables can provide reliable energy to everyone all the time, which is the task of modern utilities.

Consider my native state of Washington, where wind is now the source of between a quarter and third of the total load -- the sort of figure Lovins touts in his reply. But wind-power managers for Energy Northwest, Washington's consortium of 28 public power utilities, said last month that the state grid's ability to absorb intermittent renewable energy is "about maxed out." Because much wind power is produced when demand is low, millions of dollars' worth of power is "curtailed"--that is, the windmills are turned off. As a result, the state is furiously investigating methods to store the excess energy, methods of the sort that apparently Lovins doesn't think they need. Similarly, New Jersey, a state cheered by Lovins, has cut investments in renewable energy supplies but is investigating energy storage.

Washington and New Jersey are not alone. As a rule, to repeat a point in my article, it is difficult with today's technology to reach above a certain limit with renewables. (Typically engineers believe the limit to be about 30 percent of the total power load, but some argue for lower numbers.) Surpassing that figure, according to a January study by two researchers at the Stanford Global Climate and Energy Project, will be difficult without "grid-scale energy storage" --methods for storing truly large amounts of power. Building these will be so expensive that in many cases the costs of construction "will prohibit their deployment." Even when energy-storage facilities can be built, the researchers concluded, revamping the grid is so difficult that the work "will require decades."

Against these persistent difficulties, the continued presence of large amounts of relatively affordable petroleum** -- the subject of my article -- is of obvious import. If natural gas, either from shale or methane hydrate, is a ready alternative, the transition to renewables will be even more difficult. Lovins' Pollyannaish refusal to see the real obstacles ahead will only make them more difficult to surmount.

* Why the difference between the German Industrial Energy Companies and Lovins's claim that "German power reliability rose to the highest in the European Union"? The reason is that Lovins's figure only covers blackouts lasting longer than three minutes. But the real problem with renewables is large numbers of very short outages--modern industrial equipment is so sensitive that even a few milliseconds of power fluctuation can cause severe damage.

** Lovins denigrates my use of "petroleum" to mean both oil and gas. It is true that people in the energy industry have specific definitions for the word. But among the general public, my usage is common. If Lovins doesn't believe this, he can look at the Encyclopedia Britannica or even Wikipedia, which define the word in this way ("in common usage [the term] includes all liquid, gaseous, and solid hydrocarbons"). Good grief.